This invention relates to fiber optic connectors and optical fiber systems.
Fiber optic connectors couple optical communication channels (e.g., optical fibers) to one or more optical devices (e.g., electro-optic and opto-electric devices). The optical communication channels may be defined by a bundle of glass or plastic fibers (a xe2x80x9cfiber optic cablexe2x80x9d), each of which is capable of transmitting data independently of the other fibers. Relative to traditional metal connections, optical fibers have a much greater bandwidth, they are less susceptible to interference, and they are much thinner and lighter. Because of these advantageous physical and data transmission properties, efforts have been made to integrate fiber optics into computer system designs. For example, in a local area network, fiber optics may be used to connect a plurality of local computers to each other and to centralized equipment, such as servers and printers. In this arrangement, each local computer has an optical transceiver for transmitting and receiving optical information. The optical transceiver may be mounted on a printed circuit board that supports one or more integrated circuits. Typically, each computer includes several printed circuit boards that are plugged into the sockets of a common backplane. The backplane may be active (i.e., it includes logic circuitry for performing computing functions) or it may be passive (i.e., it does not include any logic circuitry). An external network fiber optic cable may be connected to the optical transceiver through a fiber optic connector that is coupled to the backplane.
Other fiber optic applications have been proposed. For example, backplanes have been designed to interconnect the circuit boards of a computer system and thereby enable optical communication between the boards (see, e.g., U.S. Pat. Nos. 4,913,508, 5,134,679, and 5,793,919). These backplanes often are referred to as xe2x80x9coptical backplanes.xe2x80x9d Typically, an optical backplane includes one or more fiber optic cables that couple to connectors mounted on the edges of the printed circuit boards.
The invention features an optical fiber system that enables direct board-to-board optical communication that does not require data transmission through the backplane. In accordance with this inventive optical fiber system, a positioner is configured to urge opposite ends of two or more optical fibers respectively toward opposed optical devices that are coupled to facing sides of adjacent printed circuit boards coupled to a common backplane.
Embodiments may include one or more of the following features.
The positioner may be configured to support the optical fibers along a curved path between the opposed optical devices. The ends of the optical fibers preferably extend beyond respective ends of the positioner. The positioner preferably is configured to hold the optical fibers in a spaced-apart, substantially parallel planar array. The positioner may be configured to align end portions of the optical fibers in directions oriented at oblique angles relative to respective engagement surfaces of the opposed optical devices.
In one embodiment, the positioner includes a flexible and resilient support structure that extends along a substantial length of the optical fibers. The support structure preferably includes a flexible and resilient ribbon matrix. The ribbon matrix may incorporate an elongated resilient member that increases the resiliency of the ribbon matrix. The positioner and the optical fibers preferably form a unitary, elongated fiber optic ribbon having a planar surface bounded by two ends and two sides. The ends of the optical fibers preferably extend beyond respective ends of the fiber optic ribbon. The fiber optic ribbon may preferentially bends in a plane orthogonal to the planar surface upon application of a compressive force between the ends of the fiber optic ribbon. The fiber optic ribbon preferably is elastically bendable.
In another embodiment, the optical fibers are incorporated in a multi-fiber fiber optic cable and the positioner is configured to releasably receive the multi-fiber fiber optic cable. The positioner preferably has a support arm configured to guide the optical fibers into alignment with the opposed optical devices. The support arm may include two or more support fingers. The positioner may include a second support arm with two or more support fingers that interleave with the support fingers of the first support arm. The positioner preferably is pivotally coupled to each of the opposed optical devices.
The positioner may be characterized by an engaged configuration in which the optical fibers are optically coupled to the opposed optical devices and a disengaged configuration in which the optical fibers are optically de-coupled from the opposed optical devices. The positioner may include a biasing mechanism configured to switch the positioner between the engaged configuration and the disengaged configuration upon application of a centralized pressing force. The biasing mechanism preferably includes a spring coupled between the positioner and one of the opposed optical devices.
Among the advantages of the invention are the following. The invention provides an optical fiber system that enables direct board-to-board optical communication without the complexity and possible communication delays that would be required if data transmissions had to go through the backplane. In addition, each inventive optical fiber system may be installed and removed quickly and easily. Furthermore, the invention may be readily retrofitted into existing computer systems.
Other features and advantages of the invention will become apparent from the following description, including the drawings and the claims.